Biofilm formation in surface and drinking water distribution systems in Mafikeng, South Africa

Abstract

Poor quality source water and poorly treated reused wastewater may result in poor quality drinking water that has a higher potential to form biofilms. A biofilm is a group of microorganisms which adhere to a surface. We investigated biofilm growth in the drinking water distribution systems in the Mafikeng area, in the North- West Province of South Africa. Analysis was conducted to determine the presence of faecal coliforms, total coliforms, Pseudomonas spp. and Aeromonas spp. in the biofilms. Biofilms were grown on a device that contained copper and galvanised steel coupons. A mini tap filter – a point-of-use treatment device which can be used at a single faucet – was also used to collect samples. Scanning electron microscopy demonstrated that multi-species biofilms developed on all the coupons as well as on the point-of-use filters. Galvanised steel and carbon filters had the highest density of biofilm. Total coliforms, faecal coliforms and Pseudomonas spp. were isolated from raw water biofilm coupons only. Aeromonas spp. and Pseudomonas spp. were isolated from filters. The susceptibility of selected isolates was tested against 11 antibiotics of clinical interest. The most prevalent antibiotic resistance phenotype observed was KF-AP-C-E-OT-K-TM-A. The presence of virulence genes was determined using the polymerase chain reaction. These results indicate that bacteria present in the water have the ability to colonise as biofilms and drinking water biofilms may be a reservoir for opportunistic bacteria including Pseudomonas and Aeromonas species.

Characterisation of Vibrio Species from Surface and Drinking Water Sources and Assessment of Biocontrol Potentials of Their Bacteriophages

“…The number of water samples collected from different areas is presented in Supplementary Table 1 . These sites were selected because previous studies in the North West province have revealed the presence of virulent and multidrug-resistant strains in either food or water samples [ 30 – 34 ]. The choice of these sites not only reflects the desire to contribute towards finding potential solutions regarding the worrying trends associated with challenges of treating infections resulting from the spread of resistant bacterial strains within communities but also in addressing problems that are common in our immediate local environment.…”

“…Unfortunately, microbial contamination of such unprotected water bodies is a significant cause of a large proportion of water-associated epidemics [ 27 – 29 ]. The significant number of reports confirming the presence of pathogenic microorganisms in water consumed by people in rural communities in the North West province of South Africa also informed the need to conduct the study [ 30 – 34 ]. Thus, in this study, virulent Vibrio species of water samples collected from taps, boreholes, and dams in the North West Province, South Africa, were characterised, and the lytic potentials of Vibrio -specific bacteriophages were assessed for potential exploitation of biocontrol agents against pathogenic Vibrio strains.…”

Biofilm Production Potential of Salmonella Serovars Isolated from Chickens in North West Province, South Africa

“… Malangu and Ogunbanjo (2009) reported an acute Salmonella poisoning in 2005 emanating from South African Hospitals. Biofilm production was reported in drinking water ( Mulamattathil et al 2014 ), while Isoken (2015) reported the isolation of biofilm-forming Salmonella species in cabbage and spinach sold in South Africa. The presence of Salmonella species in food and water provides opportunities for cross-contamination along the food chain and accounts for diseases in susceptible individuals ( Karkey et al 2016 ; Byrd-Bredbenner, 2017 ).…”

Phosphate deficiency induced biofilm formation of Burkholderia on insoluble phosphate granules plays a pivotal role for maximum release of soluble phosphate

“…Biofilm formation in drinking water pipe network is a major cause for deterioration of water quality and also for operational problems. It is responsible for the increase of pathogenic bacterial load, decrease of dissolved oxygen, change of taste and odor, and red or black coloration of supplied drinking water 7 . On the other hand, biological wastewater treatment is getting much attention in the recent years and bacterial biofilms impart significant roles for such treatments.…”